The present invention relates to a system that provides pictorial information on board of a vehicle.
A recently developed on-board pictorial source system, used as a navigation (NAVI) system for a vehicle, provides pictorial information such as road map information or the like for vehicle riders to order to facilitate vehicle driving. This system has seen practical use. When this navigation system is used, the road map information is displayed on a screen of a display device which is located within or at least in the vicinity of a instrument panel in front of the vehicle driver. Therefore, this system is very convenient for the vehicle driver because he can with ease successively confirm the destination, the current position, and so on, even while he is driving the car.
By using the navigation system, it is possible to provide not only the road map information but pictorial information such as operational data for the vehicle, a maintenance guide, various kinds of warning and the like. Further, it is possible to provide pictorial information such as explaining a procedure. Such a procedure would be a repair procedure for a break-down condition in the case where the break-down condition has been displayed by the maintenance guide. Furthermore, in the case where map information is displayed on the screen, it is possible to selectively display information showing locations of gasoline service stations, restaurants, hotels, etc., in addition to the map information which is mainly composed of roadway information.
It is, however, necessary to store data for the information in a memory to make it possible to provide such various kinds of pictorial information, as described above. If a conventional and generally known semiconductor memory is employed as the memory for this pictorial information, a large number of memories are required because the amount of data to be stored is very large. As a result, the system is increased in size and its cost is high.
Recently, on the other hand, an on-board audio player has been developed and manufactured which can play a digital audio disc, that is, the so-called compact disc (CD). The playback is performed with high-fidelity even within a car where the playback conditions are poor. This CD can be utilized not only as an audio disc but as a ROM (read only memory) to store data for video pictorial information or the like. A CD used for such data will be called a CD-ROM. If it is possible to use this CD-ROM as a memory in an on-board pictorial information display system, it is believed that the use of such a CD-ROM would be very advantageous in view of the reduction in size as well as in cost of the system because such a CD-ROM has an extremely large storage capacity as well as a short access time.
In the case where a CD-ROM is used as a memory in an onboard pictorial information source, it is desirable to have such a system in which a CD used for music (its original purpose) as well as a CD used for a ROM can both be satisfactorily and compatibly used.